Device for drying and setting the adhesive on backs of books

ABSTRACT

A device for drying and setting of backing adhesive material applied to backs of books comprising a feeder adjacent a book binding machine including a conveyor belt on which the back of the books are disposed and a gripper for holding the books in a feeding and clamping range. A plurality of HF-electrodes are positioned opposite to the backs of the book blocks and laterally with respect to a longitudinal axis relative to the conveyor belt, the electrodes being mounted in the feeding and clamping range for the gripper adjacent to the book binding machine. An exhaust is provided which removes evaporation leaving said backing adhesive material.

The present invention relates to a device for the drying and setting ofadhesive on backs of books, in particular, the backing adhesive materialwhich is applied to the backs of books.

When making books, the individual pages of a book are mechanically andsometimes manually assembled into a book block. Thereafter, this bookblock is gripped by gripping means of a book binding machine, so thatthe individual pages are not displaced with respect to each other. Inthe subsequent continuous operation of the book binding machine, theback of the book is then milled, provided with a layer of adhesive, andsubsequently a paper or gauze strip is pressed against the back of thebook. Sometimes when catalogues are bound, an envelope type material isused, so that the backing adhering material, as it is commonly called inthe trade, i.e., the strips of gauze, paper or envelopes, adhere firmlyto the backing of the book.

It is apparent that the adherence of this material on the backing of thebook is still relatively weak, since the adhesive has not set. Thesetting of the adhesive is carried out, as generally known, byevaporating the moisture contained in the adhesive, so that one can saythat the adhesive has to be dry for obtaining a rigid connection betweenthe backing adhesive material and the back of the books.

Only when the rigid connection has been obtained after the adhesive isset, the book block may be subjected to further manufacturing processes,for example, the trimming of the fold extensions in a so-called threeknife trimmer.

In practice, it has been shown that the drying of the adhesive withrespect to the remainder of the manufacturing operational speed of theknown book binding machines takes too long, so that a number of devicesare known to accelerate the setting of the adhesive. Almost all of thesedevices are similar in that they are all switched in series with respectto the book binding machines and cannot be considered as an integralpart of the book binding machine. Therefore, the book blocks must beremoved from the feeding device and fed to the drying station.

In the known drying devices for setting the adhesive, a number of heatsources are known in order to accelerate the rate of evaporation ofmoisture in the adhesive, for example, microwaves, hot air blowers orinfrared beams. It also had been suggested to accelerate the dryingprocess by subjecting the book block backs to a high frequency voltagefield which is created by high frequency electrodes. Hence, theshortening of the drying period is subject to certain limitations. Thisis caused by a distortion or corrugation of the back of the book due toaccelerated removal of the moisture from the adhesive which thenpenetrates into the back of the book, or by a bubble formation of theadhesive which results in an uneven adherence of the backing adhesivematerial onto the back of the book block.

For the above-mentioned reasons, the known drying devices are relativelylarge and require a lot of valuable factory space, since the books whichexit from the book binding machine are released at a certain intervalwhich does not coincide with the speed of the drying device, so that aback-up situation is created which is caused by the drying device andhas to be somehow absorbed by the same.

Besides the fact that the known devices may accelerate the drying of theadhesive, there is still the disadvantageous ratio of speed between theknown book binding machines and the drying device. However, the evengreater disadvantage is that the books must be removed from the feedingmeans of the book binding machine and moved to the drying device whichrequires additional operators and therefore increased costs, and in thatthe quality of the books may suffer because at the time of removal ofthe books from the transport gripping means, the adhesive is still "wet"which may lead to a displacement of the individual pages or to thepartial or complete removal of the backing adhesive material from thebacks of the books. Therefore, the books are often pushed against atable plate in order to return the books to their desired correct formor position.

In order to prevent these disadvantages, a device for drying theadhesive was suggested, wherein the books are held in a flat band chainpair for clamping and feeding the books, whereby within the totalclamping and feedng range, an adhesive applying means and the clampingstations are arranged in series with respect to each other, and whereinthe drying station consists of short wave infrared beams which aredirected onto the backs of the books and are installed at a lowdistance, that is, 20mm away from the books.

With these devices, it is to be attempted to dry the book backs duringthe time they are positioned on the flat band chain.

However, for various reasons, the desired success cannot be obtained.First of all, it is almost impossible to move the chain plates at theabsolute same speed at all times, so that the book which is held betweentwo plates is disturbed due to the uneven movement of the chains. If thedrying and setting of the adhesive is carried out at this point, thereis absolutely no possibility to see to it that the books have theoriginal desired shape.

Furthermore, the desired success cannot be obtained because when usingthe short wave infrared beams by means of a direct application, thelower side of the adhesive layer is first dried and then gradually thecomplete drying of the adhesive layer takes place.

Furthermore, the use of the infrared beam causes a dangerous heating ofthe book pages, so that the paper may be damaged, for example, it maybecome corrugated due to the moisture which is removed from the adhesivewhich may be an irreversible situation.

It is therefore an object of the present invention to provide a devicecomprising a plurality of high frequency electrodes which are positionedopposite to the book backs and laterally with respect to thelongitudinal axis behind a feeding band on which the other side of thebacks of the books are mounted, the electrodes being mounted in thefeeding and clamping range for the gripper of the feeder adjacent to abook binding machine, and that the device is provided with an exhaustmeans for the high frequency electrodes.

The advantages obtained with the inventive device can be seen that thedrying of the adhesive now takes place in the range where the books arestill held by the gripper of the feeder. Therefore, a displacement ofthe individual pages of the book is eliminated, so that a quality formedbook leaves the drying station with the backing adhesive materialsecurely connected with the back of the books. The books will now be fedto further manufacturing stations, whereat the drying of the books iscarried out at the same speed of the operating speed of the book bindingmachine.

Other objects and features of the present invention will become apparentfrom the following detailed description considered in connection withthe accompanying drawings which disclose the embodiments of theinvention. It is to be understood, however, that the drawings aredesigned for the purpose of illustration only and not as a definition ofthe limits of the invention.

In the drawings, wherein similar reference characters denote similarelements throughout the several views:

FIG. 1 is a schematic side view of the structure of the inventivedevice;

FIG. 2 is a section taken along the lines II--II in FIG. 1;

FIG. 3 is a schematic top plan view of one possible arrangement for thehigh frequency electrodes;

FIG. 4 is a view taken in the direction of the arrow IV in FIG. 2;

FIG. 5 is a schematical side view of the gripper means and the conveyormeans of the inventive device;

FIG. 6 is a view in the direction of the arrow VI of FIG. 5;

FIG. 7 is a plan view of a book held by the feeding gripper;

FIG. 8 is a vertical sectional view through a feeder with a book held inposition;

FIG. 9 and 11 are detailed partial sectional views of the mounting ofthe high frequency electrodes;

FIG. 10 is a perspective view of a detail of the mounting of the highfrequency electrodes;

FIG. 12 is an elevational view of a further embodiment of the invention;

FIG. 13 is a high frequency power diagram;

FIG. 14 is a diagram which shows the feeding path; and

FIG. 15 is a diagram of the evaporation curve.

The inventive device as shown in FIG. 1 is a part of a well-known bookbinding machine which is not shown. The inventive drying station of theinvention is the last station of a known book binding machine. In knownmanner, the book binding machine is provided with feeding grippers 1when the books 2 are held, so that the books may be milled, glued andattached with a strip of paper, gauze or the like, while the books runthrough the book binding machine. The books are then dried in the devicein accordance with the invention.

For the purpose of drying the adhesive layer, the inventive device isprovided with so-called high frequency electrodes 3, the following beingcalled HF-electrodes for short. These HF-electrodes are positioned suchthat the back of the books 2 which are provided with the adhesive layer,are fed through the HF-field created by the HF-electrodes 3, so that thedrying of the adhesive layer is carried out, i.e., the evaporation ofthe moisture contents in the adhesive layer is removed. These so-calledHF-driers are well known, so that it is not necessary to go into adetailed discussion about the function and operation thereof. TheHF-electrodes 3 are mounted on a frame 4 which is provided with aconveyor belt 5 which runs above the HF-electrodes 3 and whereby thebook blocks 2 are supported on the conveyor belt 5. Between the conveyorbelt 5 and the HF-electrodes 3, there is provided a stationaryinsulating layer 6, which is made of a material having a low frictioncoefficient with the conveyor belt 5. Thereby, a constant mechanicalstress on the electrodes 3 is prevented.

As can be seen from FIG. 2, an adhesive layer 8 is applied on the back 7of book 2 with which a backing adhesive material 9 is bonded to thebooks 2. This backing adhesive material 9 may consist of differentmaterials, for example, paper, gauze or carton. Since this material isnot only to be applied to the back 7 of the books 2, but is also to bebonded to the adjacent area of the book, a pressure lever 11 is providedwith associated pressure springs 10 and a pressure roller 12, so that apressure force is applied on the entire range of the material 9. Theconveyor belt 5 which runs over the two transport rollers 13, runs withthe same speed as do the gripper means 1, so that a relative movementbetween the book blocks 2 and the conveyor belt 5 does not take place.

The HF-electrodes 3 are mounted on electrode supports 15 by means ofelectrode fasteners 14, the electrode supports being mounted oninsulators 16. The electrodes 3 are pushed upwardly by a spring 17against the backs 7 of the book blocks, whereby the insulation layer 6,as well as the conveyor belt 5, prevent a direct contact of theelectrodes 3 and the backing adhesive material 9.

The HF-electrodes 3 create a high frequency field through which thebooks are guided, whereby the high frequency field permits a very rapiddrying, i.e., there is obtained an evaporation of the moisture in theadhesive material. The power of the HF-electrodes 3 is such that acomplete drying and a complete setting of the adhesive layer 8 isachieved in a time period in which the book block 2 moves through thedrying device of the invention. The speed of the books is equal to theoperational speed of the book binding machine of which the drying deviceis an integral part, since the gripper means 1, wherein the book blocks2 are held, pass through the total book binding machine, including thedrying device. Since this operational speed of the book binding machineis rather high, the removal of the moisture from the adhesive layer 8must be carried out rapidly in the drying device. For this purpose, thealready mentioned high power of the electrodes 3 is required and, on theother hand, the squeezing-out of the backing adhesive material 9 at thebacks 7 of the books 2, so that an eventual formation of bubbles in theadhesive layer is prevented. A further, rather essential requirement ofthe inventive device is the provision of an air exhaust system, so as tokeep up with the enormous drying speed. In the embodiment shown in FIG.1, such an exhaust system is shown, essentially comprising a blower 18,which is mounted below the conveyor belt 5, and an exhaust means 19,which is positioned above the conveyor belt 5, on which the blocks ofbooks 2 are moved.

The frame 4 is essentially formed by a closed housing, which at itsupper portion is provided with a base plate 21 having a plurality ofapertures 20, so that the air from blower 18 may enter through baseplate 21. This housing construction also permits one to install feederlines 22 from the inside of the housing 4 and to the HF-electrodes 3.

The air exhaust which comprises a blower 18 and an exhaust 19 isnecessary because, due to the high power of the HF-electrodes 3,evaporation already starts in the first section of conveyor belt 5. Thisrelatively high amount of evaporation is released as a result of theshort rest duration. The evaporation vapor has to be removedimmediately, so that a penetration of water vapor into book 2 isabsolutely prevented, since otherwise the individual pages of the book 2would distort, which would result in a poor book quality.

As can be seen from FIG. 3, the HF-electrodes 3 are positioned obliquelywith respect to the feeding direction of the book 2, whereby theHF-electrodes 3 are arranged at different longitudinal distances withrespect to each other, along the total length of the conveyor belt 5. Atthe starting range, the electrodes are spaced closer together, while theelectrodes are spaced farther apart from each other at the center rangeof the conveyor belt, and further are spaced closer together at the endof the conveyor, so that when books 2 enter the drying device, a suddenheating of the adhesive layer 8 occurs. During the further movement ofthe books 2, this temperature is maintained, and before leaving thedrying device, the heat is increased again, so as to make sure that allthe remaining moisture has been removed from the adhesive layer 8. Thisprocedure assures that the back adhesive material 9 is fixedly connectedwith the back of the books, since the adhesive layer is completely driedand set, which permits an immediate further manufacturing step with thebooks. This procedure eliminates interruptions in the operating processduring the manufacturing which is rather time saving.

Furthermore, a very substantial advantage is obtained with the presentinvention in that the books which leave the drying station have a shapewhich is expected from a high quality book. This is achieved in that thedrying and setting of the adhesive layer 8 is carried out while the bookis still held in position by the gripper means, which prevents adisplacement of the book 2 with respect to the back adhesive material 9.

As can be seen in FIG. 1, the required and well-known elements forcreating the high frequency field are installed in the frame 4, forexample, a feeder cable 23, a condenser 24 and the actual output control25. Naturally, the structure shown in FIGS. 1 and 3 may be varied withthe drying device in accordance with the invention. For example, FIG. 10shows that the spring or resilient mounting or bearing for theHF-electrodes 3 can be obtained in a manner where a cylindricalelectrode fastener 14a is screwed into electrode support 15, and thecylindrical electrode fastener 14a is encompassed by a pressure spring26 which engages the HF-electrodes 3. FIG. 11 shows that the springeffective bearing for the HF-electrodes may be eliminated completely andmay be directly mounted at the electrode fasteners 14a onto theelectrode support 15.

FIG. 12 shows one embodiment of the invention wherein the book blocks 2are fed at the lower side of conveyor belt 5 and held in position by thegripper means 1. Obviously, this is indeed a reversed process to that ofthe one shown in accordance with FIGS. 1 and 2.

FIGS. 13-15 show the distribution of the HF-power along the length ofthe conveyor belt 5, the temperature path which is the result of thispower distribution and finally the resulting evaporation curve, in thatorder. Thereby, the positionings of the HF-electrodes 3 is shown, whichat the beginning are rather spaced closely together; in the center rangethey are spaced farther apart; and at the end of the conveyor belt 5,the electrodes are again closer together. This arrangement results inthe fact, as can be seen in FIG. 14, that the adhesive layer is rapidlyheated, so that in a relatively short time period, the temperatureexceeds 100° C, and that this temperature is maintained over the totalrange of the conveyor belt. From this temperature distribution, it canbe seen that at the starting range of the conveyor belt, a very sharpincrease of the evaporation curve is obtained, that an even evaporationtakes place over the total center range, and that a total removal ofmoisture from the adhesive layer takes place at the end of the conveyorbelt 5.

While several embodiments of the present invention have been shown anddescribed, it will be obvious to those skilled in the art that manychanges and modifications may be made thereunto without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A device for drying and setting of adhesive onbacks of book blocks, in particular of backing adhesive material appliedto backs of books, comprising:a book binding machine including adjacentthereto a feeding means including a conveyor belt on which said backs ofsaid books are disposed and a gripper means for holding said books in afeeding and clamping range; a plurality of HF-electrodes positionedopposite to said backs of the book blocks and laterally with respect toa longitudinal axis relative to and under said conveyor belt, saidelectrodes being mounted in said feeding and clamping range for saidgripper means of said feeding means adjacent to said book bindingmachine, said HF-electrodes being spaced apart at different distanceswith respect to each other, the distance of the electrodes with respectto each other is substantially close together at a starting range ofsaid conveyor belt, said HF-electrodes being spaced farther apart at acenter range of said conveyor belt, and said HF-electrodes being spacedclose with respect to each other in a spacing which substantiallycorresponds to their distance spacing at said starting range of saidconveyor belt at an end of the conveyor belt; and an exhaust means forremoving evaporation leaving said backing adhesive material.
 2. Thedevice according to claim 1 wherein said HF-electrodes are springmounted.
 3. The device according to claim 1 further comprising:pressurelevers including associated pressure roller means thereon for exertingpressure in a range of said backs of said book blocks; and springsoperatively connected to and biasing said levers.
 4. The deviceaccording to claim 1 whereinsaid exhaust means comprises a blowerpositioned beneath said HF-electrodes; and an exhaust positioned abovesaid HF-electrodes.
 5. The device according to claim 1 wherein saidHF-electrodes are positioned obliquely with respect to said grippermeans.
 6. The device according to claim 1 further comprising:astationary insulating layer disposed between said conveyor belt and saidHF-electrodes.
 7. The device according to claim 6 wherein saidinsulating layer comprises a material having a low friction coefficientwith said conveyor belt.
 8. The device according to claim 1 wherein thespeed of said conveyor belt corresponds to the speed of said grippermeans.
 9. The device according to claim 1 further comprising:asubstantially closed frame having an upper base plate with a pluralityof apertures; insulators are mounted on said upper base plate; andelectrode support means disposed in said insulators for mounting saidHF-electrodes on an upper side of said base plate.